The present invention relates to an assembly of a self-locking hex head screw and a self-locking hex nut that use parallel screw threads of one or various types that lock against each other upon applying a torque. The resulting counteracting torque forces provided by the screw thread types are further enhanced secured in place by applying a physical lock using press fit surfaces on the nut and finally a snap ring that prevents these threads from prying loose. The assembly resembles a mechanism or machine-like action where three different phase actions take place in tandem to ensure a fixed lock. These rapid-to-install all-in-one, self-locking ABC Fasteners can be used without additional flat, tension or split washers as an assembly and can be used as individual parts as in the case of a single screw or a single nut. These ABC Fasteners can be used in a variety of industries and applications where vibration or fluids tends to loosen typical screws made of either fine or course threads.